Hadronic cross section measurements with the DAMPE space mission using 20GeV-10TeV cosmic-ray protons and $^4$He

TL;DR

This paper reports precise measurements of the inelastic cross sections of cosmic-ray protons and helium nuclei on a heavy target over a wide energy range, improving flux normalization and providing first data for helium at high energies.

Contribution

It presents the first high-energy inelastic cross section measurements for helium nuclei on a heavy target, improving cosmic-ray flux models.

Findings

Significant improvement in cosmic-ray flux normalization.

First cross section measurements for helium nuclei above 10 GeV/n.

Extended energy range for proton and helium inelastic cross sections.

Abstract

Precise direct cosmic-ray (CR) measurements provide an important probe to study the energetic particle sources in our Galaxy, and the interstellar environment through which these particles propagate. Uncertainties on hadronic models, ion-nucleon cross sections in particular, are currently the limiting factor towards obtaining more accurate CR ion flux measurements with calorimetric space-based experiments. We present an energy-dependent measurement of the inelastic cross section of protons and helium-4 nuclei (alpha particles) on a Bi$_4$Ge$_3$O$_{12}$ target, using 88 months of data collected by the DAMPE space mission. The kinetic energy range per nucleon of the measurement points ranges from 18 GeV to 9 TeV for protons, and from 5 GeV/n to 3 TeV/n for helium-4 nuclei. Our results lead to a significant improvement of the CR flux normalisation. In the case of helium-4, these results correspond to the first cross section measurements on a heavy target material at energies above 10 GeV/n.